Global Feature Not Properly Fetched When self.global_object != "GLOBAL"

Dear SALT developers,

We noticed an issue in the SALTModel class that may affect models relying on custom global feature names.

1. Bug: Global Feature Hardcoded Key

In this line:

x_global = inputs.get("GLOBAL", None)

The code uses the hardcoded key "GLOBAL" instead of self.global_object. This causes x_global to be None even if a global feature exists under a different key like "events". As a fix, we suggest updating the line to:

x_global = inputs.get(self.global_object, None)

2. Feature Proposal: Configurable Global Feature Concatenation

We also propose to make the concatenation of the global feature with the embedded representation optional. This can be controlled via a boolean toggle in the config file, e.g.,

concat_global: false  # default: false

This provides more flexibility for users and ensures backward compatibility with existing configurations that do not use global feature concatenation.